The present invention relates to twist-on connectors for electrically coupling stripped ends of a plurality of wires; and more particularly to such connectors which have a tapered metal coil within an insulating shell.
The ends of two or more wires for an electrical circuit often are connected together using a twist-on type wire connector. These connectors are available in a variety of sizes and shapes and commonly have a frusto-conical shaped shell of insulating material, such as plastic, with an opening at the larger end. The opening communicates with a similarly tapered aperture that has internal helical threads. The fastening operation is performed by inserting the stripped ends of two or more wires into the open end and rotating the connector so that the threads screw onto and twist the wires to form an electrical coupling. In an improvement of the basic connector, a tapered metal wire coil is inserted into the shell aperture engaging the threads along substantially the entire length of the coil. The conductive coil engages the bare wires and aids in providing a conductive path therebetween.
The shell is molded from plastic and thereafter the tapered metal coil is inserted into the shell aperture. Previously, either the coil or the shell had to be rotated during this insertion so that the coil turns mesh with threads of the shell aperture. Because screwing the components together is a time consuming process, alternative faster assembly techniques are desired. To that purpose, attempts were made to merely press the tapered coil into the conical threaded shell aperture without rotating those components. However, the insertion force stripped the threads of the plastic shell destroying the utility of the threads in retaining the coil in the shell.
A general object of the present invention is to provide a twist-on wire connector in which the shell and coil are adapted for rapid assembly.
Another object is to provide such a wire connector wherein the coil can be pressed into the shell with minimal damage to threads of the shell aperture.
These and other objectives are satisfied by a twist-on connector that includes a shell of electrically insulating material having a frusto-conical shape with an aperture extending from one end of the shell. The aperture has an outer tapered section adjacent to the one end with threads that engage electrical wires inserted into the aperture for connection. A beveled section of the aperture extends inwardly from the outer tapered section to a smaller diameter intermediate tapered section formed by a threadless region adjacent to the beveled section and a threaded region extending inward from the threadless region. The aperture further includes a closed end section that adjoins the intermediate tapered section.
A coil, within the aperture of the shell, has a frusto-conical shape with a larger end, a smaller end and a middle portion therebetween. The coil has a first plurality of turns at the larger end which engage the threadless region of the aperture. The smaller end engages the closed end section of the aperture with the middle portion being spaced from the shell prior to insertion of electrical wires into the aperture.
As the coil makes minimal contact with the shell prior to insertion of the wires, the coil may be pressed into the shell aperture with negligible damage to the aperture threads.